1. Technical Field
The present disclosure relates to a thin film transistor substrate and a method of manufacturing the same and, more particularly, to a thin film transistor substrate capable of appropriately maintaining driving performance, even when there is a difference between manufacturing processes, and a method of manufacturing the same.
2. Discussion of Related Art
With improvements in information technology, there is an increasing demand for display devices having a large size and a small thickness. CRT displays according to the related art, however, are insufficient to meet the demand. Therefore, flat display devices, such as a PDP (plasma display panel), a PALC (plasma address liquid crystal display panel), an LCD (liquid crystal display), and an OLED (organic light emitting diode) device, are in great demand.
In general, a display device includes a lower substrate having thin film transistors formed thereon, an upper substrate opposite to the lower substrate, and a liquid crystal layer interposed between the two substrates. An electric field applied to the liquid crystal layer is adjusted to display images. The display device further includes gate and data drivers that drive a display panel.
In the display device, the gate driver driving the display panel includes a gate driving integrated circuit (IC), and the gate driving IC is mounted in a TCP (tape carrier package) or COG (chip on the glass) technique. Other methods, however, that are advantageous in terms of manufacturing cost, size of products, and design have been developed. For example, instead of the gate driving IC, a gate driver that uses an amorphous silicon thin film transistor (hereinafter referred to as a-Si TFT) to generate a gate signal is mounted to a glass substrate of a display panel.
The driving performance of the thin film transistor greatly depends on differences between manufacturing processes. More specifically, in a process of exposing a photoresist layer, the width and the shape of the channel of the thin film transistor depend on the amount of light radiated to the photoresist layer. Therefore, a structure capable of appropriately maintaining a driving performance, even when there is a difference between manufacturing processes, is needed.